A variety of devices have been taught for controlling the communication of gas entering and leaving the respiratory system. For example, for supplying gases other than those present in the ambient environment, to modify the ambient environment or for collecting exhaled gases for testing.
This can be done by covering the head with a hood-like device, or by covering the whole face or just the mouth and nose with a mask or by directing gas flow through the mouth by means of a mouthpiece.
A mouthpiece to function as a conduit for gases to and from the lungs has features which are intended to (a) hold it in place, (b) effect a seal to ensure all gases passing the mouth can only pass through the mouthpiece. In cases where it is desired to have control of all of the gases entering or leaving the respiratory system, features must be incorporated to either block the nose or collect all gases passing through the nose as well.
U.S. Pat. No. 1,050,620 to De Ford teaches a mouthpiece having a tube of oval cross section for introduction between the teeth to act as an air passage as well as to hold the mouthpiece in place. U.S. Pat. No. 2,521,084 to Oberto teaches a tray following the contour of the teeth. This tray is used to hold the mouthpiece in place as well as to keep the teeth apart and thus prevent obstruction of the internal opening of the mouthpiece's air passage. U.S. Pat. No. 1,592,345 to Drager teaches a mouthpiece held in place by the teeth which are wedged between a flared section of the mouthpiece on their labial side and a different flared section on their lingual side. U.S. Pat. No. 3,207,154 to Rubilotta teaches two wedge shaped projections from the mouthpiece designed to fit between the teeth for the purpose of stablization of the mouthpiece and to separate the teeth to allow free passage of air through the mouthpiece. De Ford and Drager also teach head harness and neck straps to hold the mouthpiece in place.
Holding the mouthpiece in place by use of the teeth has some disadvantages. Holding the mouth open for more than a few minutes is very uncomfortable. It is very difficult to swallow with the mouth open. On the other hand loosening the force on the mouthpiece or opening the mouth may lead to loss of seal of the mouthpiece or its dislodgement from the mouth. Straps prevent rapid engagement and disengagement of mouthpiece and would make it unsuitable for most uses.
De Ford effects a seal by means of an inflatable flange surrounding the mouth. U.S. Pat. No. 4,030,493 to Walters teaches effecting a seal by means of an oval flange that is held to the mouth by hand when the mouthpiece is in the mouth. U.S. Pat. No. 4,470,413 to Warncke teaches the internal opening to the mouthpiece is surrounded by an oval flange that fits around the inside of the mouth opening between the lips and the teeth. These seals require constant effort and attention for effectiveness.
U.S. Pat. No. 4,470,413 to Warncke teaches a mask attachment to the mouthpiece which blocks the nose when the mouthpiece is in place. U.S. Pat. No. 2,521,084 to Oberto teaches a mask covering the nose forming a common gas passage between the mouthpiece and the nose. The mask is held in place by the mouthpiece which in turn is held in place by the teeth, putting further stress on the jaw muscles. Further, the mask has a large non-respiratory tract dead air space, which is not desirable for the collection of test gases.
It is therefore an object of this invention to provide an improved device through which a person may breathe through the mouth.
It is a further object of this invention to provide an improved device through which a person may breathe through both the mouth and nostrils.
It is a further object of this invention to provide an improved device through which a person may breathe through either the mouth or in another aspect through both the mouth and nostrils, which forms a more effective and comfortable seal with the mouth or the mouth and nostrils, and may be held in place sufficient to form an effective seal without the use of straps or the necessity of a person gripping the device with the teeth.
Further and other objects of the invention will be apparent of those skilled in the art from the following summary of the invention and detailed description thereof.